A number of dihydrocinnamaldehyde (3-phenylpropionaldehyde) derivatives are important compounds in the fragrance industry, such as
3-[p-isopropylphenyl]-2-methyl-propionaldehyde also known as Cyclamen Aldehyde PA1 3-[p-tert-butylphenyl]-2-methyl-propionaldehyde PA1 3-[3,4-methylenedioxyphenyl]-2-methyl-propionaldehyde also known as Helional PA1 3-[p-methoxyphenyl]-2-methyl-propionaldehyde PA1 3-[p-tert-butylphenyl]-propionaldehyde PA1 3-[p-n-butylphenyl]-2-methyl-propionaldehyde PA1 3-[p-iso-butylphenyl]-2-methyl-propionaldehyde PA1 3-[p-.alpha.-methylpropyl-phenyl]-2-methyl-propionaldehyde PA1 3-[p-tert-butylphenyl]-3-methyl-propionaldehyde. PA1 R.sup.1 together with R.sup.2 represents the methylene dioxy group; and PA1 R.sup.3, R.sup.4 and R.sup.5 are hydrogen or methyl.
W. Berends and L. M. v.d. Linde discuss a number of dihydrocinnamaldehyde derivatives with regard to odor properties and method of synthesis in Perfumery and Essential Oil Record, 58, 372 (1967).
One of the methods described involved the reaction of a benzene nucleus with an .alpha.-ethylenic aldehyde or, preferably, with the corresponding alken-2-ylidene diacylates in the presence of titanium tetrachloride as catalyst. This method is described further in U.S. Pat. No. 3,023,247 wherein it is indicated that titanium tetrachloride is unique in its ability to direct the reaction in the desired manner.